Heat exchangers or devices for enhancing or facilitating the flow of heat are numerous in the art. They exist in a range of sizes and for a wide range of applications. The smallest are included, for instance, in miniature cryocoolers for infrared thermal imaging, superconducting electronic applications, and the like. At the other extreme, the largest heat exchangers are those found in electric power stations. In either case, the thermal performance of heat exchangers is generally related to the frictional pressure drop or static pressure drop through the heat sink.
It is well known for turbulent flow that the thermal ability of a heat exchanger can be improved by increasing the ability of the air mover to overcome resistance to flow or static pressure losses through the heat sink. Experience indicates that with narrow fluid passageways in the heat sink, static pressure plays a prominent role in the thermal performance of the heat exchanger. A suitable air moving element, such as a blower or fan, is usually structurally associated with the heat sink to aid in facilitating the heat transfer process. This is done by increasing the surface area of the heated body or surface in contact with the cooling air stream. Another technique to improve the heat transfer process is to increase the air velocity through the heat sink. Both of the above techniques involves decreasing the thermal resistance of the component surface to the air stream.
Depicted in FIG. 1, a prior art heat exchanger 1 for electronic devices typically employs a tubeaxial fan 2 directly mounted to the heat sink 3 having a plurality of fins 4. These existing devices, of the type illustrated in FIG. 1, are generally limited in the amount of fin surface area that can be provided for any given heat sink volume, due to the limited static pressure capability of the tubeaxial fan 2. Remote mounted blowers may also be used but, they have the inherent disadvantage of not offering a compact solution that can run independent from the rest of the system. In addition, having a remote mounted blower complicates the design due to the routing of the ducting. Where compact systems are required, these remote blowers are not an option. A shortcoming of the tubeaxial fan is its inability to overcome any appreciable resistance to airflow. Increasing the fin surface area increases the airflow resistance that the tubeaxial fan must overcome. At some point, increasing the surface area will decrease heat sink performance, as the fan invariably becomes the limiting factor in the amount of air flow resistance it can overcome. Thus, for a given heat sink volume, there is a limit to the thermal resistance that a direct mounted tubeaxial fan can provide.
Therefore, there persists a need for a heat exchanger that is compact, has an air mover that supplies enough power to generate high air velocities and to overcome static pressure in the heat sink, is reliable and requires low maintenance, and that is inexpensive to manufacture.